Data processing devices are often used to control clock dependent functions, such as the transmission of data in communication systems and the control of specific functions in control systems. For example, a control system can be used to control a motor assembly or the duration and/or timing of specific events. In systems having multiple processing devices, it is often necessary to calibrate devices so that one device can indicate to another device when, or how long, an event is to occur. If the devices are not calibrated in some manner, there is little guarantee that the desired time event will be realized as expected. In one embodiment, the devices are calibrated by using a common clock. However, devices with a common clock generally require dedicated hardware, such as clock drivers and clock signal pins, to receive a clock signal from the common clock among the devices.
In another prior-art solution, clocks of devices within a data processing system are calibrated by trimming the devices to meet a specific time requirement. In such a data processing system, the devices are allowed to run asynchronously, eliminating a need for a common clock signal, as well as dedicated clock drivers and pins to support the common clock signal. However, the clocks within the devices may still deviate with temperature, and require the devices to be trimmed during production to improve calibration. It is costly to maintain and trim devices during production for calibration purposes.
From the above discussion it should be apparent that an improved method of calibrating timing in a remote device to a main device is needed.